OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

An aldehyde H can be split

Eg in ethanal CH3CHO, the aldehyde H would be a quartet due to the adjacent CH3 group

in the data sheet, the ones with * would not be splitting in the diagram shown in exam. http://www.ocr.org.uk/Images/74947-datasheet.pdf , and aldehyde is not one of them.

Reply 1441

lai812matthew

10

Original post by fannehh

When asked to identify what feature causes stereoisomerism, is it just any double bound in the molecule?

and chiral carbon

Reply 1442

afeerak

june 2015 markscheme and paper unit 4

F324_MS_June15.pdf622.8KB

F324-01 QP Jun15.pdf544.2KB

Reply 1443

fannehh

2

Original post by lai812matthew

and chiral carbon

Thanks!

Reply 1444

Jehaan

19

Original post by fannehh

When asked to identify what feature causes stereoisomerism, is it just any double bound in the molecule?

Non rotation around a c=c bond as well as different substituent groups
And optical isomerism where a carbon has 4 different substituent groups so it is chiral so forms a non superimposable mirror image

Reply 1445

Jehaan

19

Original post by Chem1stry101

If you have symmetry and one environment is mirrored elsewhere in the molecule, just look at one side for the splitting pattern.

Eg if you had CH3-CH2-O-CH2-CH3 it is symmetrical. So only 2 H environments. The CH3 peak would be a triplet due to the neighbouring CH2, and the CH2 would be a quartet due the neighbouring CH3

But just to check if you had CH3CH2CH2CH3 the CH3 would be split into a triplet but the CH2 would not be split as its symmetrical?

Reply 1446

yoda123

15

Really wish the exam was in the morning, gonna be stressing over it until 13:45

Reply 1447

Jehaan

19

Original post by yoda123

Really wish the exam was in the morning, gonna be stressing over it until 13:45

I agree especially as I have two exams the next day and one on Thursday so I'm not really going to be able to revise much for the ones on wednesday

Reply 1448

ranz

5

Original post by yoda123

Really wish the exam was in the morning, gonna be stressing over it until 13:45

same, just cba!

Posted from TSR Mobile

Reply 1449

ranz

5

Original post by Jehaan

But just to check if you had CH3CH2CH2CH3 the CH3 would be split into a triplet but the CH2 would not be split as its symmetrical?

ch2 would split into quartet right?

Posted from TSR Mobile

Reply 1450

yoda123

15

Do u use pencil for displayed formula, skeletal, etc and do you have to use pencil

Reply 1451

rahma1994

what do I write for bonding and structure for benzene??

good luck guys btw

Reply 1452

GEEKSruletheworld!

14

Can carboxylic acids be reduced by NABH4 aswell?

Reply 1453

thesmallman

9

Original post by Chem1stry101

If you have symmetry and one environment is mirrored elsewhere in the molecule, just look at one side for the splitting pattern.

Eg if you had CH3-CH2-O-CH2-CH3 it is symmetrical. So only 2 H environments. The CH3 peak would be a triplet due to the neighbouring CH2, and the CH2 would be a quartet due the neighbouring CH3

But in this case, the two CH2 groups would be in the same environment (peak integration:4), and the two CH3 groups will also be in the same environment (peak integration:6)
Would the peak representing the two CH2 groups not be split into a septet tho because there is a CH3 group neighbouring each of them (so 6 neighbouring protons in total?)
And vice versa, the peak representing the two CH3 groups will be a quintet?
Soz I'm confused af lol

Reply 1454

Chem1stry101

1

Original post by ranz

ch2 would split into quartet right?

Posted from TSR Mobile

Right

Reply 1455

Jehaan

19

Original post by ranz

ch2 would split into quartet right?

Posted from TSR Mobile

I did a legacy paper and I think the answer said that it can't be split as it can't split itself if that makes sense

Reply 1456

rahma1994

also, do aromatics have a splitting patters?

Reply 1457

Jehaan

19

No

Original post by GEEKSruletheworld!

Can carboxylic acids be reduced by NABH4 aswell?

Reply 1458

Chem1stry101

1

Original post by thesmallman

But in this case, the two CH2 groups would be in the same environment (peak integration:4), and the two CH3 groups will also be in the same environment (peak integration:6)
Would the peak representing the two CH2 groups not be split into a septet tho because there is a CH3 group neighbouring each of them (so 6 neighbouring protons in total?)
And vice versa, the peak representing the two CH3 groups will be a quintet?
Soz I'm confused af lol

No my splitting pattern description was correct. And integration would be 2:3 not 4:6 as its simplified

Reply 1459

Jehaan

19

Original post by rahma1994

what do I write for bonding and structure for benzene??

good luck guys btw

Overlap of p orbitals = pi bonds
Overlap of more land 2 carbons=delocalised electrons
Benzene has a delocalised ring system
The 6 electrons are shared over 6 carbons give a low electron density
Benzene is planar, with bond angles of 120 degrees
That's all I can think of

OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

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